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55 | <H3><A NAME="SECTION0082123000000000000000"></A><A NAME="optparse-handling-boolean-options"></A> | |
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57 | 6.21.2.3 Handling boolean (flag) options | |
58 | </H3> | |
59 | ||
60 | <P> | |
61 | Flag options--set a variable to true or false when a particular option | |
62 | is seen--are quite common. <tt class="module">optparse</tt> supports them with two separate | |
63 | actions, <code>store_true</code> and <code>store_false</code>. For example, you might have a | |
64 | <code>verbose</code> flag that is turned on with <code>"-v"</code> and off with <code>"-q"</code>: | |
65 | <div class="verbatim"><pre> | |
66 | parser.add_option("-v", action="store_true", dest="verbose") | |
67 | parser.add_option("-q", action="store_false", dest="verbose") | |
68 | </pre></div> | |
69 | ||
70 | <P> | |
71 | Here we have two different options with the same destination, which is | |
72 | perfectly OK. (It just means you have to be a bit careful when setting | |
73 | default values--see below.) | |
74 | ||
75 | <P> | |
76 | When <tt class="module">optparse</tt> encounters <code>"-v"</code> on the command line, it sets | |
77 | <code>options.verbose</code> to <code>True</code>; when it encounters <code>"-q"</code>, | |
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